So have you had a lot of problems with these then?, because I've used them over the years and haven't!.
After all, they are used in "domestic" applications and compared to the belling lee co-ax are a better connector in that even if they do use the centre conductor at least there is one less thing to go wrong.
Just "how" many aerial installers solder the centre conductor or even just "crimp" it with a pair of side cutters?. Even the outer braiding can be screwed onto the connector which is much better then the usual way the BL is used.
So why did satellite receiver manufactures chose to standardise on the F then?.
After all I couldn't even imagine domestic gear using BNC, TNC, or N or
7/16th types now, could U...
If you want a really useless abomination of a connector then the PL259 is the one:((
It does hold together though - and to be fair it was designed in the late 30's when "UHF" was anything over 100MHz. Its top frequency is only 300MHz and its quite depressing to see kit supposedly working at a GHz with these connectors.
In the U.S., where F connectors etc. are used for cable TV, it also deskills the termination exercise. I somehow doubt that a lot of the individuals doing this work would have a high success rate with BNC and TNC et al. connectors.
Think we might be getting mixed up - I was referring to the "UHF Plug" (PL259) when referring to a top frequency of 300 MHz.
Which was one of its design aims.
Many don't do too well with what they have. An elderly neighbour of ours was told by the highly skilled CAI member aerial destructor that she couldn't get digital TV because, as he told me, there were "not enough decibels being received and they were interfering with each other so you need a system amplification installation and new cable installed" (and here is your bill so far for GBP150).
As our aerial (propped up on the attic water tank 10 years ago to see if it would work and it's going to be fixed properly one day honest) works perfectly this puzzled me until a quick look showed the skilled fitter had pointed the aerial about 25deg out at the Kodak Building rather than the transmitter. This actually does give the strongest signal on the idiotbox measuring device he was using but is useless as it also includes numerous out of phase reflections. 10 minutes work got a perfectly good signal (and I did enjoy telling the installers exactly what they could do with their bill).
Even as an explanation to a lay person, that's bogus.
AIUI, the critical factors are the carrier to noise ratio (because DTTV carrier is NdB below the analogue (typically adjacent) carriers and the bit error rate.
The elderly person might be confused by the introduction of BERT into the discussion but even so.....
Hmmm. As I would have thought that he would have got a lower error rate reading by pointing the antenna at the transmitter, presumably he was using a simple signal strength meter.
It's going to be interesting to see how these characters get on when and if there are no analogue transmissions where they could at least look for multipath reception on the picture.
Not necessarily nasty, but I think we'll have to agree to differ on this.
Note the word "receptacles" in there which makes it clear they're referring to the female side of the interface, which (as I've already said) is what primarily determines the RL/VSWR performance.
Well you're wrong: they can, and do. Here's some evidence
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A VSWR of 1:1.22 is not achievable with a plug using a wire centre > conductor.
Why not? - RF-wise the male F connector amounts to an open cable end with a flange attached to the outer conductor.
Here's an example of a good-quality F back-back female coupler:
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IME the RL specs on that page are not exaggerated.
A good one might, but there are plenty of grotty BNC connectors about.
Data sheets for the the female connectors would be more pertinent, but I agree they're not always available. But armed with a VNA and the HP cal kit, measurements aren't too difficult.
Well I'd agree they aren't suitable for use in aggressive atmospheres where corrosion would be likely to be a problem. In practice though in TV distribution systems I've never known this to be a problem, other then in outdoor applications where the sealing has failed and water has got in. Most real-world problems arise from faulty installation or poor crimping, leading to bad connection in the outer conductor, not the inner. (And of course we're not considering transmission applications here with significant RF power, where passive intermod might be a problem.)
Its RF properties can be excellent, especially given what you pay.
You'll find lots of F-connectors on the capital plant side in CATV and SMATV systems, etc. - so it's not strictly limited to consumer applications.
My list of worse RF connectors:
- RCA phono (aka Cinch) - used as a UHF connector in some TV tuners and modulators; now that *is* nasty;
- miniature version of the Belling Lee - remember those?
I try to avoid anything to do with them. Every time I get involved with the damn things I know what is going to happen - you touch the cable and the connector self destructs. Sometimes looking at them hard is enough to make the cable jump out.
One local installer of these things seems to use his teeth to crimp them and a passing breeze makes them fall apart. Another sort which seems popular around here has what I presume is a crimp skirt made of tinplate the thickness of aluminium foil and about 3mm in depth. Needless to say it has the breaking strain of a jellybaby.
Because the impedance is very dependent upon the geometry of the inner and outer conductors - and a bit of copper wire sticking out the end doesn't stay absolutely straight nor round. Moreover the oxidation of the copper introduces regions of variable conductivity, and worse, small amounts of rectification. All these factors degrade the VSWR.
Those are specifications for a fixed coupler - the figures are those I would expect for any such device (even a PL259 coupler!!) as its only a tube with a fixed inner.
That figure is a fairly representative one for BNC/TNC, even fairly cheap ones will achieve it.
The reason the data sheets are not available is that the performance is inconsistent. This is inevitable if you have something where the plug is partially constructed on site. I agree you can always do real measurements - but I doubt if that happens very much.
It isn't a problem because you are rarely working at the limits of performance. It does mean the connectors are not suitable for situations where consistent performance is a critical issue.
I wouldn't disagree with that :-).
Ah, yes I had rather forgotten that one although I never considered it to be anything other than a poor audio connector!
This is a recommendation? Every TV set has a Belling Lee plug, they don't fall over in droves but its still an 'orrible connector.
Cheapest of all, I agree. However, is the cost of plugs an important factor in any installation? You can buy F type connectors for about
10p each or less, however I doubt if you would use those plugs. You only need one poor connector and an hour or so fault finding wipes out the cost saving of the cheap plugs.
Agreed - but I still don't consider it to be an RF connector :-)
Well from the way you put it these are falling to bits as soon as anyone looks at them, which isn't true. If any installers have difficulty terminating the F plug then perhaps they should be *terminated* from the job....
OK then. An N type will cost a few quid now can you really see domestic grade manufacturers using them?. No I don't think so. The F is a simple inexpensive way to do a simple undemanding job. Which they are quite good at.
We use connectors on transmission equipment that cost around 80 odd quid a go, which are very good for what they do but domestic users aren't likely to be dealing with kilowatt's of RF:!.
As to domestic grade equipment give me an F over the Belling Lee pox any day..
No...
But then again how many domestic users would use XLR grade??
But can you see the average Sky installer being able to make off a BNC connector properly? Most of them can just about manage to nail the dish on your front door and run.
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